Gasoline containing ashless dispersant

ABSTRACT

An amide derived from an aliphatic polyamine and a high molecular weight monocarboxylic acid is used as an additive for a gasoline composition to impart cleanliness characteristics thereto by reducing the formation of deposits in the carburetor of an internal combustion engine in which the gasoline is burned. The high molecular weight monocarboxylic acid can be prepared by the reaction of a halogenated 600 to 3,000 molecular weight polymer of a C2 to C5 mono-olefin with an alpha, beta-unsaturated monocarboxylic acid of from 3 to 8 carbon atoms. Particularly useful is the amide prepared from tetraethylene pentamine and polyisobutenyl propionic acid, the latter being obtained from acrylic acid and from polyisobutylene of average molecular weight within the range of about 800 to 1,900.

United States Patent Chandler GASOLINE CONTAINING ASHLESS DISPERSANT [75] Inventor: Roger E. Chandler, Westfield, NJ.

[73] Assignee: Exxon Research and Engineering Company, Linden, NJ.

[22] Filed: Dec. 17, 1970 [21] Appl. No.: 99,321

Related U.S. Application Data [63] Continuation-in-part of Ser. No. 657,532, Aug. 1, 1967, abandoned, which is a continuation-in-part of Ser. No. 337,187, Jan. 13, 1964, abandoned.

[52] U.S. Cl. 44/71 [51] Int. Cl Cl0l 1/22 [58] Field of Search 44/63, 66, 71', 260/268 S, 260/404.5; 252/401 [56] References Cited UNITED STATES PATENTS 3,219,666 11/1965 Norman et al 252/51.5 A

Primary Examiner-Daniel E. Wyman Assistant Examiner-Y. H. Smith Attorney, Agent, or Firm-Byron O. Dimmick; Frank T. .lohmann 1 [5 7] ABSTRACT An amide derived from an aliphatic polyamine and a high molecular weight monocarboxylic acid is used as an additive for a gasoline composition to impart cleanliness characteristics thereto by reducing the formation of deposits in the carburetor of an internal combustion engine in which the gasoline is burned. The high molecular weight monocarboxylic acid can be prepared by the reaction of a halogenated 600 'to 3,000 molecular weight polymer of a C to C monoolefin with an alpha, beta-unsaturated monocarboxylic acid of from 3 to 8 carbon atoms. Particularly useful is the amide prepared from tetraethylene pentamine and polyisobutenyl propionic acid, the latter being obtained from acrylic acid and from polyisobutylene of average molecular weight within the range of about 800 to 1,900.

3 Claims, No Drawings GASOLINE CONTAINING ASHLESS DISPERSANT REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of copending application Ser. No. 657,532, filed Aug. 1, 1967, now abandoned, and entitled Gasoline Containing Ashless Dispersant, that application being in turn a continuation-in-part of application Ser. No. 337,187, filed Jan. 13, 1964, and entitled Carboxylic Acids and Dispersants Derived Therefrom," said application Ser. No 337,187 now being abandoned.

DESCRIPTION OF THE INVENTION The present invention concerns a gasoline composition that has been improved with respect to deposit formation tendencies associated with the operation of an engine using said gasoline composition. While modern day gasoline engine design has promoted the efficient utilization of gasolines and while the gasolines themselves have been tailored to make the best use of this efficiency, gasoline engine operation is not entirely trouble free. Complete combustion of the fuel in the combustion chamber of the engine seldom, if ever, occurs. It is believed that some of the unburned hydrocarbons from the gasoline undergo complex cracking, polymerization, and oxidation reactions, leading to insoluble materials which form deposits within the combustion chamber. Some of these degradation products also find their way into the crankcase of the engine and thereby contribute to the formation of lubricating oil sludge.

Another problem that is encountered in the operation of the gasoline engine is the accumulation of deposits in the carburetor of the engine. One of the major contributors to this type of deposit is the combustion products exhausted from other motor vehicles in traffic, as well as fumes generated by the engine itself. Such fumes include blow-by gases which accumulate under the hood of the engine. These carburetor deposits collect principally on the throttle and throttle body and cause rough idling.

Still another source of trouble in the operation of modern day engines is the positive crankcase ventilation system which is required on automotive engines to minimize contamination of the atmosphere. Despite the fact that the effluent from the positive crankcase ventilation valve (PCV valve) enters the fuel intake system beyond the carburetor, there is sufficient backmixing of fumes that the use of a PCV valve greatly increases the tendency for deposits to form on the carburetor throats.

It is thus seen that a material that can be added to gasoline that will impart carburetor detergency properties will be of considerable benefit in the operation of a gasoline engine. Any modification of a gasoline composition which operates to reduce the formation of engine deposits, crankcase sludge, carburetor deposits, PCV valve plugging and the like can be referred to as imparting engine cleanliness.

It has now'been found, in accordance with the present invention, that cleanliness of a gasoline can be greatly improved by incorporating therein a minor portion of an oil-soluble amide dispersant derived from an aliphatic polyamine and a high molecular weight monocarboxylic acid having a molecular weight in the general range of about 600 to 3,000. More particularly, such dispersant additive can be prepared by condensing a halogenated, high molecular weight, olefin polymer with an alpha, beta-unsaturated monocarboxylic acid to form a high molecular weight acid having a long aliphatic chain and, subsequently reacting the latter acid with a polyalkylene polyamine under conditions causing amide formation. These dispersants can also be prepared by first forming an aliphatic alcohol ester of the high molecular weight acid and then condensing the ester with the polyalkylene polyamine. Such esters can be prepared by condensing the halogenated high molecular weight polymer with an ester of an alpha, beta-unsaturated monocarboxylic acid.

To prepare the high molecular weight carboxylic acids or esters that are employed in this invention, the preferred starting material is a polymer of a C to C mono-olefin, e.g., polyethylene, polypropylene or polyisobutylene, wherein the olefin polymer has an average molecular weight within the range of from about 600 to about 3,000. Especially useful products are obtained when the molecular weight range is about 800 to about 1,900. Such polymers have in the range of from about 40 to 250 carbon atoms, and more preferably within the range of about 50 to about carbon atoms, per molecule. The selected polymer is halogenated with either bromine or chlorine, preferably the latter, using sufficient halogen to provide about one to two atoms per molecule of the olefin polymer. The halogenation step can be conducted in the temperature range of from about ordinary ambient temperatures to about 250F. To aid in the halogenation step, the polymer can be dissolved in a suitable solvent, such as carbon tetrachloride, in order to lower the viscosity of the polymer, although the use of such a solvent is not necessary.

The time required for halogenation may be varied to some extent by the rate at which the halogen is introduced. Ordinarily from about 2 to about 5 hours is a satifactory halogenation period. In a representative plant scale operation involving the chlorination of polyisobutylene of 830 molecular weight, a l00-pound batch will be chlorinated with 10 pounds of chlorine introduced into the reactor over a period of 3% hours with a chlorination temperature of about 250F.

The halogenated polymer thus obtained is condensed with an alpha,beta-unsaturated, monocarboxylic acid of from 3 to 8 carbon atoms. Ordinarily, because of their greater availability, acids of this class having 3 to 4 carbon atoms will be used. Such acids include acrylic acid, alpha-methylacrylic acid (i.e., 2-methyl propenoic acid) and crotonic or isocrotonic acid (betamethylacrylic acid). Other alpha-beta-unsaturated acids that may be employed include tiglic acid (alpha, methylcrotonic acid), angelic acid (alphamethylisocrotonic acid), sorbic acid, and cinnamic acid.

In an alternate preparation the halogenated polymer can be condensed with an ester of the C to C unsaturated monocarboxylic acid, e.g., ethyl methacrylate, in place of the free acid. The esters that can be used in this alternate preparation are those of aliphatic alcohols having from 1 to 10 carbon atoms, including methyl, ethyl, isopropyl, isobutyl, amyl, hexyl, 2- ethylhexyl, decyl, and C oxo alcohols. Such esters include amyl acrylate, isopropyl methacrylate, butyl crotonate, methyl acrylate, etc. In the subsequent amidation reaction an alcohol will be split out in place of water. The higher boiling the alcohol, the more difficult will be the removal of the alcohol from the reaction 3 mixture. Generally, alcohols boiling above about 285F. will not be desirable for this reason. Furthermore, use of higher boiling alcohols represents an economic disadvantage in that excess weights of material are thus being put intothe reaction only to be removed later. Most preferably, the esters that willbe used here are those of C to C aliphatic alcohols.

ln condensing the halogenated polyolefin with the alpha,beta-unsaturated acid or with an aliphatic ester thereof, at least one mole of acid or ester is used per mole of halogenated polyolefin. Normally, the acid or its ester will be employed in excess and may amountto as much as 1.5 to 2 moles per mole of halogenated polyolefin. The condensation temperature can be in the range of from about 300 to 500F. and will more preferably be within' the range of from about 375 to 475F. The condensation may require from about 3 to about 24 hours but will ordinarily take place in from 6 to 18 hours. After the reaction has been completed, excess acid or ester can be purged from the mixture, for example, by blowing with a stream of nitrogen at a temperature of 400 to 500F.

The high molecular weight carboxylic acids or esters used in the invention can also be prepared by a socalled one-step process involving the halogenation of the olefin polymer in the presence of the alpha-betaunsaturated acid or its ester. Using proportions of reactants" within the ranges discussed above, the starting acid or ester and the olefin polymer are mixed together in the reactor, the temperature being kept below about 150F. until the start of halogen introduction so as to avoid homopolymerization of the alpha, betaunsaturated acid or ester. Once halogenation has begun/the temperature may be raised to as high as 250F. After halogen introduction the temperature may be raised to 300 to 500F. to effect the condensation reaction i v The high molecular weight carboxylic acid or ester obtained by the foregoing procedure is further reacted with a' polyalkylen e polyamine under conditions favoring amide formation. Generally, the mole ratio of acid or its ester to polyamine will be in the range of 1:1 to 3:1, although higher ratios, i.e., as high as 5:1, may be employed if there are sufficient amino groups in the polyamine. I

The aliphatic polyamine that is employed in preparing the reaction products of the present invention can be an alkylene polyamine fitting the following general formula:

wherein n is 2 to 3 and m is a number from 0 to 10. Specific compounds coming within the formula include diethylene triamine, tetraethylene pentamine, dipropylene triamine, octaethylene nonamine, and tetrapropylene pentami'ne. N,N-di-(2-aminoethyl) ethylenediamine can also be used. Other aliphatic polyamino compounds that can be used are the N-aminoalkylpiperazin'es of'the formula:

wherein n is a number from 1 to 3, and R is hydrogen or an aminoalkyl radical containing 1 to 3 carbon atoms. Specific examples include N-(Z -aminoethyl) pi- 4 perazine', N-(2-aminoisopropyl) piperazine, and N,N'- (2aminoethyl) piperazine.

The use of mixtures of alkylene polyamines, mixtures of N-aminoalkyl piperazines; and mixtures of the alkylene polyamines with the N-aminoalkyl piperazines is also contemplated, and the term aliphatic polyamine is intended to embrace all of these materials.

The reaction temperature for amide formation will generally be in the range of from about 200 to 400F. In most cases, a narrower range of from about 250 to about 350F. will be used. The reaction time will de pend to some extent upon the reaction temperature. The composition of the reaction can be determined by measuring the amount of water or alcohol that is split off during the reaction. If desired, an entraining agent such as heptane can be employed to remove the water or alcohol as an azeotrope.

The dispersant additives of the invention are conveniently prepared as concentrates in a mineral oil fraction, usually a lubricating oil fraction, for ease of handling. Such concentrates can contain from about 10 to 80 wt. of additive, on an active ingredient basis, the balance being mineral oil.

The dispersant additives of this invention will be used in concentrations within the range of about 5 to 50 or preferably 10 to 50 pounds of actual additive, i.e., amide product, per thousand barrels of gasoline 1 barrel 42 US. gallons). A concentration of 0.004 wt. is approximately 10 pounds per thousand barrels of gasoline. If 25 pounds of dispersant concentrate, containing 60 wt. of actual dispersant, is added to 1,000 barrles of gasoline, the amount of actual additive will be 15 p.t.b. (pounds per thousand barrels).

The gasolines in which the additives of this invention are employed are conventional petroleum distillate fuels boiling in the gasoline range and intended for internal combustion engines, preferably spark ignition engines. Gasoline is defined as a mixture of liquid hydrocarbons having an initial boiling point in the range of about to 135F. and a final boiling point in the range of about 250 to 450F. Gasolines are supplied in a number of different grades, depending upon the type of service for which they are intended. The additives of the invention may be employed in all of these grades but are particularly useful in motor and aviation gasolines. Motor gasolines include those defined by ASTM Specification D-439-58T, Types A, B and C. They are composed of a mixture of various types of hydrocarbons, including aromatics, olefins, paraffins, isoparaffins, naphthenes, and, occasionally, diolefins. Suitable gaseolines to which the additives of the instant invention can be added include those having an octane number range of to 105 or higher, such as a clear octane number of over 90, for example, over or 100, and comprising at least 10% by volume of aromatic hydrocarbons and less than 30% by volume of olefinic hydrocarbonsfThese fuels are derived from petroleum crude oil by refining processes such as fractional distillation, catalytic cracking, hydroforming, alkylation, isomerization, polymerization and solvent extraction. Motor gasolines normally have boiling ranges between about 70 and about 450F., while aviation gasolines have narrower boiling ranges'of between and 330F. The vapor pressures of gasoline as determined by ASTM Method D-86 vary between about 7 and about 15 psi at 100F. The amide dispersants of this invention may also be employed in aviation gasolines, which have properties similar to those of motor gasolines, but normally have somewhat higher octane numbers and narrower boiling ranges. The properties of aviation gasolines are set forth in U.S. Military Specification MIL- F-5572 and ASTM Specification D-9l0-57T.

The additives employed in accordance with this invention may be used in gasolines with other additive agents conventionally used in such fuels. It is common practice to employ from about 0.5 to about 7.0 cc./gal. of alkyl lead antiknock agents, such as tetraethyl lead, tetramethyl lead, dimethyl diethyl lead or a similar alkyl lead antiknock agent or olefinic lead antiknock agents such as tetravinyl lead, triethyl vinyl lead, and the like, or a combination thereof, both in motor gasolines and in aviation gasolines, e.g., 1.0 to 3.0 cc. of a tetraethyl-lead-tetramethyl-lead combination. Antiknock agents may also include other organometallic additives containing lead, iron, nickel, lithium, manganese and the like. Other additives such as those conventionally employed in gasolines may be used such as rust inhibitors, corrosion inhibitors, antioxidants, dehazers, demulsifiers, antistatic agents, lead octane appreciators, e.g., t-butyl acetate, auxiliary scavengers like tri- B-chloroethyl phosphate, dyes, anti-icing agents, e.g., isopropanol, hexylene glycol, and the like. It is frequently desirable also to incorporate a solvent oil into the gasoline in order to reduce intake valve deposits. If a solvent oil is used, it may be convenient to blend the dispersant and the solvent oil together and add the blend to the gasoline. A particularly preferred solvent oil will have a boiling range within the limits of about 350 to 800 F. at 10 mm of mercury pressure. More preferably, the boiling range is about 400 to 700F. at the reduced pressure. Solvent oils having a viscosity within the range of 45 to 150 SSU at 210F. are usually preferred.

The invention will be further understood from the following examples which include a preferred embodiment.

PART I PREPARATION OF HIGHER MOLECULAR WEIGHT ACIDS Preparation A A solution was prepared consisting of 2,000 grams of polyisobutylene of 950 molecular weight dissolved in 1,000 grams of carbon tetrachloride. Chlorine gas was bubbled through the stirred solution at ambient temperatures for a period of 4 hours. Following the chlorination step, the carbon tetrachloride solvent was removed from the mixture by purging with nitrogen at 285F. The chlorinated polyisobutylene had a chlorine content of 4.33%.

A mixture of 600 grams of the chlorinated polyisobutylene thus prepared and 55 grams of acrylic acid was heated to 450F. over a period of 18 hours. Hydrogen chloride was evolved from the mixture during this heating. The mixture was then purged with nitrogen for one-half hour at 450F., after which the mixture was cooled to 250F. and filtered through Dicalite filter aid (diatomaceous earth). The product, identified as polyisobutenyl propionic acid, contained 0.3 wt. of chlorine and had a saponification number of 52.1 mg. KOH/gm.

Preparation B Polyisobutylene (800 g. of a material having a molecular weight of 830) and acrylic acid (80 grams) were heated to F. Chlorine was introduced into the reaction mixture at a rate of 400 cc./min. and the temperature was increased to 250F. The chlorination was terminated after 2 hours and the temperature was raised to 425F. for 18 hours. The reaction mixture was then purged with nitrogen for 1 hour at 425F., cooled to 250F. and filtered with the aid of Dicalite. The product had a saponification number of 38 mg. KOH/g. The infrared spectrum was identical to that of the acid prepared by the two-step procedure. The product had a chlorine content of 0.42%.

Preparation C Preparation D Chlorinated polybutene (250 grams of a product obtained by chlorinating polyisobutylene of 950 molecu-.

lar weight and containiing 4.18% chlorine) and 27.5 grams of crontonic acid were heated to 450F. for a total of 20 hours. The product was purged with nitrogen at 450F. for one-half hour, cooled to 250F. and filtered through Dicalite filter aid. The product had a saponification number, of 18.3 mg. KOH/g. and was further characterized as an acid by infrared spectroscopy.

PART II PREPARATION OF AMIDE DISPERSANTS Example 1 A mixture of 355 grams of polyisobuten'yl propionic acid prepared as described in Preparation A, 132 grams of a solvent mineral oil SUS viscosity at 100F.) and 44 grams of tetraethylene pentamine was heated with stirring to 300F. for 5 hours, during which time the mixture was continuously purged with nitrogen to remove water formed during the condensation of the acid and the polyamine. The product of the reaction was filtered through Dicalite diatomaceous earth and was found to contain 2.63% nitrogen.

Example 2 The procedure outlined in Example 1 was used with the following exceptions: 443 g. (0.34 mole) of polyisobutenyl propionic acid of saponification number 43 mg. KOH/g. (prepared in the manner of Preparation A, 19 g. (0.1 mole) tetraethylene pentamine and 194 g. solvent neutral mineral oil were used. Theproduct contained 1.02% N (Theory is 1.02% N).

Example 3 An 800-gram of polyisobutylene of 950 molecular weightwas heated to 200F. and then treated with a stream of chlorine for 4 hours at that temperature at a chlorine feed rate of 200 cc. per minute. The temperature was then reduced to 150F. and 105.6 grams of ethyl acrylate was added. Then the temperature was raised to 425F. and maintained at that level for 5 hours after which the reaction mixture was stripped with a stream of nitrogen to remove unreacted ethyl acrylate. The product thereby obtained had a saponification number of 34.2 mg. KOH per gram and its infrared spectrum was found to be consistent with an ester of polyisobutenyl propionic acid.

A 400-gram portion of the polybutenyl propionic ester prepared as just desribed was diluted with 176 grams of a solvent neutral mineral oil (150 SSU at 100F.) and the mixture thereby obtained was treated with 18 grams of tetraethylene pentamine at 300F. for 18 hours, the mixture being purged with a stream of nitrogen during the entire reaction period in order to remove ethanol as it was formed. The reaction mixture was then filtered while hot, using diatomaceous earth filter aid. Analysis of the product showed a nitrogen content of 0.53 wt. The product was found to be similar in all respects to that obtained by the procedure of Example 2.

Example 4 The procedure of Example 3 is repeated, but instead of ethyl acrylate the chlorinated polyisobutylene is reacted with 106 grams of methyl methacrylate, yielding an ester product having a saponification number of 40 mg. KOH per gram. Then a 700gram portion of the ester product is diluted with 300 grams of solvent neutral mineral lubricating oil and the mixture is treated with 34.3 grams of diethylene triamine, following the reaction procedure and conditions described in Example 3.

Example 5 Polyisobutenyl propionic acid (540 g., 0.5 mole of the product of Preparation A) solvent neutral mineral oil (250 g.) and diethylene triamine (51.5 g., 0.5 mole) are heated to 300F. while the reaction mixture is purged with nitrogen for 3 to 6 hours to remove the water of reaction. The product is filtered through diatomaceous earth filter aid. The nitrogen content is 2.5%.

Example 6 Polyisobutenyl propionic acid (540 g., 0.5 mole of the product of Preparation A), solvent neutral mineral oil (256 g.) and N-aminoethylpiperazine (64.5 g., 0.5 mole) are heated to 300F. while the reaction mixture is purged with nitrogen for 3 to 6 hours to remove the water of reaction. The product is filtered through diatomaceous earth filter aid. The nitrogen content is 2.47%.

Example 7 Polyisobutenyl propionic acid (500 grams, 0.4 mole) prepared as in Preparation A and having a saponification number of 48 mg. KOH/g., tetraethylene pentamine (38 g., 0.2 mole), solvent 150 neutral diluent oil (228 g.)'and heptane (80 g.) were heated to reflux (292299F.) for a total of 6 hours during which time 9.5 ml. of water was collected in the Dean-Stark trap. The heptane was removed by purging with nitrogen on a steam bath and the product was filtered through Dicalite filter aid. The product had 1.65 wt. nitrogen (theory 1.76%). Amide structure was confirmed by infrared spectroscopy.

Example 8 A l l0-pound portion of polyisobutylene of 780 mopolyisobutylene there was added 10.5 pounds of acrylic I acid. Over a period of 2 hours the temperature was raised from 250 to 425F. and the pressure was increased to 20 psig. Heating was continued for 5 hours at 425F. and the reaction vessel was vented to maintain the pressure of 20 psig. The pressure was then released and the mixture was purged with nitrogen for 2 hours to remove unreacted acrylic acid. The polyisobutenyl propionic acid thereby obtained at the end of the reaction weighed 109.3 pounds and had a total neutralization number (ASTM D-664) of 46.2 milligrams of KOl-I per gram. The chlorine content was found to be 0.3 wt.

A 638-gram portion of the polyisobutenyl propionic acid obtained as just described was mixed with 352 grams of a solvent neutral mineral oil (150 SSU at F.) and the mixture thereby obtained was treated with 61 grams of tetraethylene pentamine at 300F. for 6 hours, the mixture being purged with a stream of nitrogen during the 6-hour reaction period to remove water as it was formed. The reaction mixture was then filtered through diatomaceous earth. The product analyzed 1.8% nitrogen and was in the form of a concentrate containing 66 wt. of reaction product and 34 wt. of diluent mineral oil (Concentrate 8-A).

Another portion (70 pounds) of the polyisobutenyl propionic acid prepared as just described was mixed with 31.5 pounds ofa solvent neutral mineral oil of SSU at 100F. The mixture thereby obtained was treated with 3.38 pounds of tetraethylene pentamine at 300F. under 28 inches of vacuum and using nitrogen stripping. The mole ratio of acid to amine was about 3 to 1. At the end of a 9-hour reaction period, the product was filtered through diatomaceous earth and was found on analysis to contain 1.2 wt. of nitrogen (Concentate 8-B). Yield of product was 98.5 pounds. The concentrate contained about 60 weight percent of amide reaction product.

PART III GASOLINE COMPOSITIONS Example 9 To a gasoline having an initial boiling point of 85F., a 50% point of 205F., and a final boiling point of 380F. (ASTM D-86), said gasoline containing 17.5 vol. aromatics, 11.7 vol. olefins, and 70.8 vol.'% saturates, and having added thereto 3.1 cc. of lead tetraethyl per gallon, .there is added by simplemixing sufficient of the product concentrate of Example 5 to give a concentration of amide reaction product of 21 pounds per thousand barrels of gasoline.

Example 10' The effect of an additive of the present invention in reducing crankcase oil sludging and PCV valve plugging was determined by the following tests:

Nine 1964 Ford cars, each equipped with a new cubic inch displacement 6-cylinder engine, were used in taxicab service. Each engine was fitted with a closed PCV system using an orifice type metering valve. Each 1 car. wasrun for 12,000 miles. Three of the taxis were valve failures, the sludge merit ratings obtained with each of the three groups of taxis, and the average weight of observed carburetor deposits in each of the three groups of taxicabs are given in Table I, which follows. In the table, p.t.b. means pounds per thousand barrels.

TABLE I Results for Taxicabs Operated With:

Base Fuel Plus Base Fuel Plus 25 p.t.b. Additive 50 p.t.b. Additive Base Fuel Concentrate 8-B Concentrate 8-B Average miles per PCV valve 1310 2400 3980 failure Valve Failures:

First 6000 miles 9 7 1 Second 6000 miles 18 8 6 Total 12000 miles 27 7 Three-Cab Average CRC Sludge Volume 20.5 11.0 7.5

CRC Merits 2.4 3.8 4.6

Three-Cab Average Carburetor Deposits, mg. 300 I90 120 been blended additive Concentrate 8-8 in the amount of lbs. per thousand barrels of fuel. The third set of three taxis was operated with a gasoline composition consisting of the base fuel to which had been added the additive Concentrate 8-B in the amount of 50 lbs. per thousand barrels of gasoline. The additive in each case was blended into the gasoline by simple mixing. Each of the taxis was run for a total of 12,000 miles, with the crankcase oil being drained and replenished every 3.000 miles. The crankcase oil was an SAE 20/20W oil of premium grade having an ASTM MS Sequence V rating of 35.

During the course of the taxi tests the flow capacity of the PCV valves was measured at frequent intervals. When the high manifold vacuum or low speed flow capacity of a particular valve had dropped to half that of a new valve, the valve was considered a failure and was replaced with a new one. The number of miles driven in each instance until valve failure occurred was recorded as a measure of the valve life. The number of valves that failed during the test period for each group of three taxis was also recorded.

At the end of the 12,000 mile test period, the taxi engines were inspected by disassembling them sufficiently to permit visual examination of several of the parts. These parts were visually and quantitatively rated for sludge deposits, using a CRC sludge merit rating system in which a numerical rating of 10 represents a perfectly clean part and the numerical scale decreases to a minimum value representing a part covered with the maximum sludge possible. The several merit ratings are averaged to give an overall merit rating.

Additionally, at the end of the l2,000 mile test period, the throttle body and throttle plate of the carburetor from each of the taxis were removed from the engines and washed in chloroform. This dissolved deposits from the throttle body and throttle plate. Each of the resulting chloroform solutions was heated to drive off the chloroform and the residues were weighed.

The average PCV valve life, the number of PCV It will be noted from the results shown in Table I that additive 8-8 at a treating level of 25 lbs. of additive concentrate per thousand barrels of gasoline approximately doubled the valve life and that a treating rate of 50 lbs. of additive concentrate per thousand barrels the valve life was tripled over that of the base fuel without the dispersant additive.

As to the number of valve failures occurring during the length of the tests, only about half as many valve failures occurred during the 12,000 mile period when the gasoline contained 25 lbs. per thousand barrels of the additive concentrate as compared with the fuel without the additive, and only about one fourth as many valve failures occurred when the gasoline contained 50 lbs. per thousand barrels of the additive concentrate. The second test period, i.e., from 6,000 to 12,000 miles was considerably more severe than the first period of 6,000 miles, because of greater blow-by as the engine ages in service. The test results indicate that incorporation of the additive into the gasoline will reduce the number of PCV valve replacements that will be needed during the life of an automobile and will also reduce maintenance costs by extending the life of the PCV valves.

As regards the sludge mesurements at the end of the 12,000 mile period, it was observed that use of the additive at the rate of 25 lbs. of concentrate per thousand barrels of gasoline reduced sludge volume by almost one-half and that use of the additive at a rate of 50 lbs. of concentrate per thousand barrels of gasoline reduced the sludge volume by almost two-thirds as compared with the base fuel.

It is to be noted that at a rate of 25 lbs. of concentrate per thousand barrels of gasoline, the additive reduced carburetor deposits by about one-third and that at a rate of about 50 lbs. of concentrate per thousand barrels of fuel, the additive gave almost a two-thirds reduction in deposits. This reduction in carburetor deposits occurred in spite of the fact that the improved PCV valve life resulting from the presence of additive in the gasoline would impose a heavier deposit load on these carburetors.

ln summary, the present invention concerns a gasoline composition which has been improved with respect to its cleanliness characteristics by adding to a major proportion of gasoline a minor but effective proportion of an amide obtained from one mole of an aliphatic polyamine and from l to 5 moles of a high molecular weight monocarboxylic acid. The high molecular weight monocarboxylic acid is the product of alkylating low molecular weight alpha, beta-unsaturated monocarboxylicacid of from 3 to 8 carbon atoms with a C to C mono-olefin polymer of from about 600 to 3,000 molecular weight. Preferably the polymer has an average molecular weight in the range of about 800 to about 1,900. The alkylation can be effected by halogenating the polymer and then condensing the resulting halogenated product with the alpha,beta-unsaturated low molecular weight monocarboxylic acid. Amidation is brought about by heating the polyamine and the high molecular weight acid under conditions causing the splitting out of water. As an alternative procedure, a lower alcohol ester of the high molecular weight acid is used for amidation, in which event an alcohol is split out instead of water when forming the amide.

Improvement in cleanliness characteristics includes imparting carburetor detergency action to the gasoline, reducing sludge formation in the crankcase and other regions of the engine in which the gasoline is burned, and the like. A

It is to be understood that this invention is not to be limited to the specific embodiments herein presented.

by way of example. The scope of the invention is to be determined by the appended claims.

What is claimed is:

l. A gasoline composition having the property of reducing the formation of deposits in the carburetor of an internal combustion engine burning gasoline, which comprises gasoline to which has been added, in the amount of from about 10 to about 50 pounds per thousand barrels of said gasoline, of an amide obtained from 1 mole of an aliphatic polyamine and in the range of from 1 to 5 moles of a high molecular weight monocarboxylic acid, said acid being the product of alkylating acrylic acid with a C to C mono-olefin polymer of from about 600 to about 3,000 molecular weight, said aliphatic polyamine being an alkylene polyamine having the formula: NH (CH [Nl-l(CH ),,],,,NH wherein n is 2 to 3 and m is a number from 0 to 10.

2. A gasoline composition as defined by claim 1, wherein the amount of additive is from about 15 to about 30 pounds per thousand barrels of gasoline.

3. A gasoline composition as defined by claim 2, wherein said high molecular weight monocarboxylic acid is polyisobutenyl propionic acid derived from acrylic acid and polyisobutylene of a molecular weight in the range of about 800 to 1,900, and the amount of said additive is about 15 pounds per 1,000 barrels of 

1. A GASOLINE COMPOSITION HAVING THE PROPERTY OF REDUCING THE FORMATION OF DEPOSITS IN THE CARBURETOR OF AN INTERNAL COMBUSTION ENGINE BURNING GASOLINE, WHICH COMPRISES GASOLINE TO WHICH HAS BEEN ADDED, IN THE AMOUNT OF FROM ABOUT 10 TO ABOUT 50 POUNDS PER THOUSAND BARRELS OF SAID GASOLINE, OF AN AMIDE OBTAINED FROM 1 MOLE OF AN ALIPHATIC POLYAMINE AND IN THE RANGE OF FROM 1 TO 5 MOLES OF A HIGH MOLECULAR WEIGHT MONOCARBOXYLIC ACID, SAID ACID BEING THE PRODUCT OF ALKYLATING ACRYLIC ACID WITH A C2 TO C5 MONO-OLEFIN POLYMER OF FROM ABOUT 600 TO ABOUT 3,000 MOLECULAR WEIGHT, SAID ALIPHATIC POLYAMINE BEING AN ALKYLENE POLYAMINE HAVING THE FORMULA: NH2(CH2)N-(NH(CH2)N)M-NH2 WHEREIN N IS 2 TO 3 AND M IS A NUMBER FROM 0 TO
 10. 2. A gasoline composition as defined by claim 1, wherein the amount of additive is from about 15 to about 30 pounds per thousand barrels of gasoline.
 3. A gasoline composition as defined by claim 2, wherein said high molecular weight monocarboxylic acid is polyisobutenyl propionic acid derived from acrylic acid and polyisobutylene of a molecular weight in the range of about 800 to 1,900, and the amount of said additive is about 15 pounds per 1,000 barrels of gasoline. 